BMW K bikes (Bricks)

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1Back to top Go down   O Rings compound Empty O Rings compound Thu Apr 30, 2020 7:49 pm

Packo

Packo
Silver member
Silver member
I am wondering if the O rings used in the engine eg. water/oil pump between the block and the pump around the coolant passage, are made of a particular material???
I am replacing an output shaft and have all other consumables on hand.
I would like to source the O rings locally but not sure if they are a particular compound eg. nitrile or vitron etc.
The ones from the usual suppliers are usually Red but when I have bought them locally in the past they are black.
Does this make a difference ???
I am in OZ


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83 K100 HRD Outfit
77 R100RS
1992 K1100 Outfit
1983 K100
    

2Back to top Go down   O Rings compound Empty Re: O Rings compound Sun May 03, 2020 8:28 pm

stanthomas

stanthomas
Silver member
Silver member
compatibility chart   will give you the basic material compatibility.

In general, nitrile and viton are good for oil and coolant. Use EPDM for brake fluid.
Nitrile and viton would traditionally be used with gasoline but these can be adversely affected by ethanol. FKMs (flouro compunds) and HNBR (hydroginated nitrile) are more resistant to heat and often used for engine seals and o-rings.

You also have to consider hardness.: typically an o-ring will have a shore-a hardness of 70, and temperature range. Some materials, e.g. PTFE, are resistant to most chemicals and have a good temperature range but are very stiff.

As for colour, typically nitrile/NBR is black, viton is brown, HNBR for aircon is green and silicone is red. But I wouldn't rely on it.

It is probably wishful thinking that the OEM material is the best for the job; your bike's well out of warranty so they don't have to fix it and there's no guarantee that what you get these days is original spec anyway. But to play safe, I'd say use OEM for things that are hard to get at, go your own way if it's cheaper for accessible seals.

    

3Back to top Go down   O Rings compound Empty Re: O Rings compound Sun May 03, 2020 9:00 pm

Point-Seven-five

Point-Seven-five
Life time member
Life time member
The only advantage to getting seals locally around here is that I don't have to wait for the mail from MaxBMW.  Prices from BMW are shockingly similar to what I pay for seals and o-rings at the local bearing supplier. Shocked


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Present:
1994 K75RT
1991 K100RS
1988 K100RS SE

Past:
1994 BMW K75S
1992 BMW K100RS
1982 Honda FT500
1979 Honda XR185
1977 Honda XL125
1974 Honda XL125
1972 OSSA Pioneer 250
1968 Kawasaki 175
    

4Back to top Go down   O Rings compound Empty Re: O Rings compound Mon May 04, 2020 12:22 am

RicK G

RicK G
admin
admin
I'm fairly sure Inge said they were silicone but I have used the black nitrile O-rings there and not had any problems.


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"Man sacrifices his health in order to make money.
Then he sacrifices money to recuperate his health.
And then he is so anxious about the future that he does not enjoy the present; the result being that he does not live in the present or the future; he lives as if he is never going to die, and then dies having never really lived."   Dalai Lama


Bikes 2004 K1200GT 1998 K1100 LT, 1993 K75 RT, 1996 K75RT, 1986 K75 GS, 1979 Z1300 Kawasaki
    

5Back to top Go down   O Rings compound Empty Re: O Rings compound Mon May 04, 2020 6:29 am

Packo

Packo
Silver member
Silver member
Thanks for the info
Couldn't find anything locally so have stuck an order on with Munich's


__________________________________________________
______________
 
83 K100 HRD Outfit
77 R100RS
1992 K1100 Outfit
1983 K100
    

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